1. Field of the Invention
The present invention relates to an electronic parts carrier tape used for packing and transporting parts and particularly electronic parts such as IC packages.
2. Description of the Related Art
FIG. 1 shows one known carrier tape of the type described. This carrier tape 1 is made of a flexible resin material, and includes recessed portions (hereinafter referred to as xe2x80x9cembossed portionsxe2x80x9d) 2 and flange portions 3. The plurality of embossed portions 2 are arranged at equal intervals in a longitudinal direction of the carrier tape 1, and serve to receive or store electronic parts, respectively. A tape-like lid member (hereinafter referred to as xe2x80x9ccover tapexe2x80x9d) is adhesively bonded to the flange portion 3 so that the electronic part, received in the embossed portion 2, will not drop through an opening of the embossed portion 2 during transport. A number of feed holes or perforations 4 are formed at equal intervals in one or both of opposite side edge portions of the carrier tape 1.
The carrier tape 1, used for packing and transporting electronic parts, is wound on a reel after it is molded, and the carrier tape is stored in this wounded condition. At this time, the upper and lower embossed portions 2, superposed together, are sometimes fitted together in a nested manner (see FIG. 2). The conventional embossed portion has such a shape that an angle Wi of inclination of an inner surface of a side wall (peripheral wall) 5 thereof relative to the open top of the embossed portion is 75 to 89xc2x0. Therefore, an outer dimension (X) of the bottom of the embossed portion is smaller than or generally equal to a dimension (Y) of the opening of the embossed portion, so that a nesting phenomenon, in which the superposed embossed portions are fitted together in a nested manner, is liable to occur.
FIGS. 3 and 4 show the cross-section of the carrier tape wound on the reel. The embossed portions of the adjacent (inner and outer) turns of the carrier tape can be superposed together by vibrations 6, developing during the transport, a force 7 of winding of the carrier tape on the reel during the forming operation, and a pressing force 8 produced when winding the carrier tape on the reel (such a pressing force can be produced when handling the wound carrier tape), and in such a case, when there is exerted an excessive force to press the upper (outer) turn of the carrier tape against the lower (inner) turn thereof, the nesting occurs.
When the nesting occurs, the carrier tape can not be smoothly unwound from the reel during the electronic parts-mounting process, and in the worst case, the unwinding of the carrier tape is stopped, thus markedly lowering the efficiency. When the carrier tape was forcibly unwound from the reel, there was a possibility of damaging the embossed portions.
It is an object of the present invention to provide an electronic parts carrier tape in which a nesting phenomenon, in which superposed embossed portions are fitted together after winding the carrier tape on a reel, is less liable to occur.
According to the feature of the present invention, there is provided an electronic parts carrier tape comprising a flexible, tape-like member having electronic part-storing embossed portions arranged at predetermined intervals in a longitudinal direction of the tape-like member;
wherein at least one rib is formed on and projects outwardly from an outer surface of a peripheral wall of each of the embossed portions, and an outer dimension (X) of a bottom of the embossed portion, as seen in a cross-section of the embossed portion through the rib, is larger than a dimension (Y) of an opening in a top of the embossed portion.
As a preferred embodiment of the present invention, the rib has a slanting portion slanting from the top of the embossed portion to the bottom thereof, and an angle Ro of inclination of an outer surface of the slanting portion of the rib relative to the top of the embossed portion is 89 to 93xc2x0.
Preferably, according to the present invention, projections are formed respectively at corner portions of an inner bottom surface of the embossed portion, and project toward the top of the embossed portion, each of the projections having one of a flat upper surface and an inclined upper surface.